code: def test_mapped_properties(self):
      x = ["a", "b"]
      y = [1, 2]
      mark = Bar(alpha=0.2)
      p = Plot(x, y, color=x, edgewidth=y).add(mark).plot()
      ax = p._figure.axes[0]
      colors = p._theme["axes.prop_cycle"].by_key()["color"]
      for i, bar in enumerate(ax.patches):
          assert bar.get_facecolor() == to_rgba(colors[i], mark.alpha)
          assert bar.get_edgecolor() == to_rgba(colors[i], 1)
      assert (
          ax.patches[0].get_linewidth() < ax.patches[1].get_linewidth()
      )
  
imports: import numpy
  import pandas
  from matplotlib.colors import to_rgba, to_rgba_array
  import pytest
  from numpy.testing import assert_array_equal
  from seaborn._core.plot import Plot
  from seaborn._marks.bar import Bar, Bars
label_desc: Use image node_id 8 for calling the TestBar obj's underlying member method code with example usage: obj.test_mapped_properties() without return types